Positive effect of eBay authentication?

[GregMitch34]

Can't be sure this is the scenario but interesting: As I am wont to do, I was checking out Heritage's "make offer to owners" feature, this time for high-graded 1933 Goudey--looking for bargain from someone who wanted cash quickly--and spotted one card I made a nice offer on, well below recent mid-May eBay sale for same type of card. The owner came back with a reasonable counter. Before going further, I fortunately noted that his card had very same PSA serial number as the card sold for a few thousand two months ago on ebay. Seemingly that sale didn't go through for some reason--and now he was ready to take half that amount from me now.

Given the timing, I am guessing--no proof--that perhaps the card did not pass PSA authenticity test and so was returned to him. Or maybe buyer just didn't pay up. In any case, now I will steer clear of it, just in case. Your thoughts?